Make WebGL extensions get lost when context is lost.

Source/core/html/canvas/WebGLCompressedTextureS3TC.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 21 matching lines @@
 
 #include <wtf/Int32Array.h>
 #include <wtf/OwnArrayPtr.h>
 
 namespace WebCore {
 
 WebGLCompressedTextureS3TC::WebGLCompressedTextureS3TC(WebGLRenderingContext* context)
     : WebGLExtension(context)
 {
     ScriptWrappable::init(this);
-    context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGB_S3TC_DXT1_EXT);
-    context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGBA_S3TC_DXT1_EXT);
-    context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGBA_S3TC_DXT3_EXT);
-    context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGBA_S3TC_DXT5_EXT);
+    enable();
 }
 
 WebGLCompressedTextureS3TC::~WebGLCompressedTextureS3TC()
 {
 }
 
+void WebGLCompressedTextureS3TC::enable()
+{
+    m_context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGB_S3TC_DXT1_EXT);
+    m_context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGBA_S3TC_DXT1_EXT);
+    m_context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGBA_S3TC_DXT3_EXT);
+    m_context->addCompressedTextureFormat(Extensions3D::COMPRESSED_RGBA_S3TC_DXT5_EXT);
+}
+
 WebGLExtension::ExtensionName WebGLCompressedTextureS3TC::getName() const
 {
     return WebGLCompressedTextureS3TCName;
 }
 
 PassOwnPtr<WebGLCompressedTextureS3TC> WebGLCompressedTextureS3TC::create(WebGLRenderingContext* context)
 {
     return adoptPtr(new WebGLCompressedTextureS3TC(context));
 }
 
 bool WebGLCompressedTextureS3TC::supported(WebGLRenderingContext* context)
 {
     Extensions3D* extensions = context->graphicsContext3D()->getExtensions();
     return extensions->supports("GL_EXT_texture_compression_s3tc")
         || (extensions->supports("GL_EXT_texture_compression_dxt1")
             && extensions->supports("GL_CHROMIUM_texture_compression_dxt3")
             && extensions->supports("GL_CHROMIUM_texture_compression_dxt5"));
 }
 
 const char* WebGLCompressedTextureS3TC::getExtensionName()
 {
     return "WEBGL_compressed_texture_s3tc";
 }
 
 } // namespace WebCore